Manjunath Doddavenkatappa, Chan Mun Choon and Ben LeongNational University of Singapore

Splash: Fast Data Dissemination with Constructive Interference in

Wireless Sensor Networks

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A Fundamental Service:Data/Program Dissemination

A dissemination protocol is required throughout the life of a sensor application

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Dissemination completion time is critical

Completion time for existing protocols is still in the order of minutes

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Culprit is Contention Resolution

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SPLA

SHConstructive Interference

[Glossy’2011]

Channel Diversity [PIP’2010]

Eliminate the need for contention

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SPLA

SHConstructive Interference

[Glossy’2011]

Channel Diversity [PIP’2010]

Eliminate the need for contention

Press escape to exit animation and then move on to the next slide

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SPLA

SHTransmission

Density Diversity

Tree Pipelining

Channel Cycling

Opportunistic Overhearing

XOR Coding

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11

Cycle 1

P1

P1

Transmitting Receiving Idling

P1P1

P1

P1

P1

P1

Cycle 2P1

Cycle 3

P2

P2

P1

P1

P1

P2P2

P2

P2

P2

P2

Cycle 4

P1

P1

P1

P1

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SPLA

SHTransmission

Density Diversity

Tree Pipelining

Channel Cycling

Opportunistic Overhearing

XOR Coding

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SPLA

SH

Channel Cycling XOR Coding

Transmission Density

Diversity

Tree Pipelining

Opportunistic Overhearing

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Constructive Interference is not Scalable [Wang et al. INFOCOM’12]

• The problem is more severe in practice

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Decreasing trend is not always true

Constructive Interference is not Scalable

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Effect of the Capture Effect

Our results suggest that an increase in no. of

transmitters can also improve reliability

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Splash: Transmission Density Diversity

• First round: only non-leaf nodes forward• Typically, more than 50% of the nodes in a tree are leaf

nodes [Manjunath et al. RTSS’11]

• Nodes benefit from low transmission density

• Second round: all nodes transmit• Nodes benefit from high transmission density by

exploiting capture effect or sender diversity [Rahul et al. SIGCOMM’10]

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SPLA

SHTransmission

Density Diversity

Tree Pipelining

Channel Cycling

Opportunistic Overhearing

XOR Coding

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Cycle 2

P1

P1

P1

P1

X

P1

Cycle 3

P2

P2

P1

P1

P1

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P1

Cycle 3

P2

P2

P1

P1

P1

P1

P1

Cycle 2

P1

P1

P1

P1

X

Packet reception chance is doubled

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SPLA

SHTransmission

Density Diversity

Tree Pipelining

Channel Cycling

Opportunistic Overhearing

XOR Coding

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CH1CH2CH3 CH4CH4CH3CH2CH1

Round 1 Round 2

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SPLA

SHTransmission

Density Diversity

Tree Pipelining

Channel Cycling

Opportunistic Overhearing

XOR Coding

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Splash: XOR Coding

•After two rounds, more than 50% of nodes received most but not full object

• Third round: every transmission is a XOR sum

• Probability that a packet transmission is useful is increased

A node in Splash has six chances to receive a packet on up to six different channels

Transmission Density Diversity

Opportunistic Overhearing

Channel Cycling

XOR Coding

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Splash: Summary of Its Three Dissemination Rounds

Three Rounds of Dissemination

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Splash: Local Recovery

• If any missing data is recovered locally

•Neighbor querying and data downloading over CSMA/CA

• Fact that about 90% of nodes have the full object makes local recovery practical

Experimental Setup

139 TelosB nodesIndriya Testbed

90 Tmotesky nodesTwist Testbed

Comparison

Splash (Contiki)

DelugeT2(TinyOS)

Other Protocols

Deluge(Contiki)

Splash DelugeT2Tree[no.]

Size[hops]

R1[%]

R2[%]

R3[%]

NR3-100%[%]

Rlr[%]

TSplash[sec]

TDelugeT2+CTP[sec]

TDelugeT2GI[sec]

1 5 84.54 97.23 98.47 91.30 100 22.49 1300 924

2 6 86.52 96.91 98.58 92.03 100 22.61 286 160

3 7 76.68 94.62 97.80 86.23 100 23.18 209 286

4 7 88.02 96.12 97.78 92.75 100 23.74 218 158

5 9 76.97 93.65 96.69 81.88 100 23.86 649 180

6 7 76.73 95.27 98.16 89.86 100 25.98 610 160

7 7 80.75 93.51 96.98 89.13 100 26.25 365 379

8 7 83.57 94.43 96.01 87.68 100 26.89 377 277

9 5 82.46 95.26 97.47 85.51 100 28.09 676 313

10 8 84.28 94.92 96.70 86.23 100 28.39 550 216

Average 82.05 95.19 97.46 88.26 100 25.15 524 305.3

Summary of Results on Indriya(32 KB dissemination)

25.15s524s 305s

/21 /12

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Summary of Results on Twist(Splash: 32 KB, Deluge: 2KB)

Splash Deluge

Tree[no.]

Size[hops]

R1[%]

R2[%]

R3[%]

NR3-100%[%]

Rlr[%]

TSplash (32KB) [sec]

TDeluge (2KB)[sec]

1 4 90.58 97.09 99.22 94.38 100 20.07 356.60

2 4 81.08 94.70 99.31 92.13 100 20.19 431.48

3 4 86.53 96.19 98.00 91.01 100 22.79 351.67

4 4 78.64 94.10 98.12 84.09 100 23.37 518.19

5 4 81.42 93.95 97.98 89.89 100 23.41 467.00

6 4 78.04 93.55 96.82 85.39 100 26.66 439.81

7 4 83.90 95.18 97.54 89.89 100 26.79 345.28

8 4 83.70 93.64 96.45 84.27 100 27.32 388.68

9 6 81.58 93.35 97.02 85.39 100 27.45 484.10

10 5 80.78 93.09 97.11 85.39 100 29.25 397.59

Average 82.62 94.48 97.76 88.18 100 24.73 418.04

24.73s418s

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Comparison to Other Approaches (Baseline: DelugeT2)

Protocol No. ofnodes

File size[KB]

Reduction factor

MNP (2005) 100 5 1.21MC-Deluge (2005) 25 24.3 1.6

Rateless Deluge (2008) 20 0.7 1.47ReXOR (2011) 16 4 1.53

ECD (2011) 25 10 1.44MT-Deluge (2011) 20 0.7 2.42

Splash 139 32 21

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Evaluation of Individual Techniques

Channel Cycling

Local Recovery

XOR codingOpportunistic Overhearing

Transmission Density Diversity

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Evaluation of Individual Techniques

XOR Coding: increases percentage of nodes having the full object from 37% to 88%

Opportunistic overhearing: decreases dissemination time by 26%

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Evaluation of Individual Techniques

Channel Cycling: decreases dissemination time by 25%

Transmission Density Diversity: 39% and 18% of nodes benefit from low and high transmission densities respectively

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Local Recovery

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Local Recovery

8s for 98.8% of 30 KB

12.4s for 1.2% of 30 KB

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Conclusion

•We designed and implemented Splash, a fast data dissemination protocol

• Key factors are constructive interference, channel diversity and techniques for reliability

• Splash reduces completion time by an order of magnitude

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Thank you

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References

Some of the images in these slides are downloaded from Google Images and Kalyan Varma’s websitehttp://kalyanvarma.net/